So now I have a solar PV system how do I make the most of it???

theboylard

If you've a diverter (ImmerSun, iBoost, SolarImmersion, plus loads of others) then it comes down to your hot water usage and the size of your tank?

For us, with an old 140 ltr hot water cylinder, our boiler went off about 3 weeks ago regarding hot water heating.
Based on last years usage, then we may flash the boiler for an hour if we do a truck load of delicate handwashing (the current mrs theboylard has a cleaning/washing fetish!!) but that will only be at most 2/3 times over the summer months?

As we use an energy guzzling power shower, then hot water usage is restricted to occasional baths & washing up.
We do have a dishwasher, and I'm trying to encourage the use of the free hot water and wash by hand, but I get incredulous looks from Lucifer and Beelzebub about washing up when there is this amazing machine that does it for you?!

Typical usage is we could probably get 2 days hot water before we might need to fire the lasers, but for us, last year the boiler went off in May and wasn't needed really until September?
Our gas bill from 8/4/14 to 25/10/14 was £70, plus the standing charge of £52.
But if I adjust to 9/5/14 to 29/9/14, then my gas bill is only £27, but the standing charge is £37!

If I narrow it further, then from 6/6/14 to 29/9/14, then the gas bill is only £5.94 and the standing charge was £30!!

Scary numbers that have made me realise that standing charge plays a massive part in my bills, thanks for making me look!

orrery

shavy65 wrote: »

Wondered how anyone else with Solar PV + immersion heater diverter got on this time of year in regards to hot water timers etc.

I turned the boiler off at the start of the month, and the water was being supported by solar prior to that. I have a 150 litre tank and a 30" immersion, and we get enough (just) for a bath and a shower each morning (I had a tepid shower one morning last week).

My daughter and her husband came to stay overnight last weekend so the boiler was turned on for an hour.

There is no reason why you can't have the boiler on once per day, with the thermostat set to about 45C and it will either turn on or not. That is how mine is set during the cold half of the year - it turns on for 1 hour and turns off again prior to us getting up in the morning to top up the water, if required.

pinnks

Given the losses between boiler and tank an alternative is to boost the water temp using the immersion itself. My Immersun has a timer or manual boost function. I imagine the other makes work similarly. Press a button and you turn the immersion on for x minutes. 15 minutes equals about 750Wh - it's just a question of the maths.


When the heating is on it makes sense to use the boiler to boost any shortfall from the solar, and any heat loss from unlagged pipes helps warm the house anyway. But once the boiler is off it is a judgement call. If I use the solar to heat our water I need between 2 and 3 kWh per day. Use the gas for water alone and it's 6 to 9 kWh.

shavy65

Thanks for the replies, very interesting!
Just goes to show how prominent the standing charge is.
I`ve always thought it was bets to avoid the immersion heater.....unless it`s free via solar obviously! I`m using the immersion diverter as mush as poss I think with the boiler topping up if required in the morning and in evening.
"If I use the solar to heat our water I need between 2 and 3 kWh per day. Use the gas for water alone and it's 6 to 9 kWh." - I assume this equates to the same amount of cash??

pinnks

Probably not far off the same amount of cash for a full day but I would imagine that if you only need to add, say 500Wh to get the water up to temp than immersion would be cheaper as you are not heating a shed load of water in the pipes.

theboylard

You need to factor in the age/efficiency of the boiler into the immersion boost/boiler conundrum.

Of it's an older boiler then it may be more efficient to use the immersion, but with a newer boiler then it's not so clear cut?

pinnks

True. My new boiler, on which the above numbers are based, cut gas consumption by about 30%.

buteman

BrummyGit wrote: »

Hi,

I went live with my 3.52 kwp system from HomeSun today. They installed an Elster AS230 meter in a cupboard and put the inverter in my loft, therefore I need to read the meter to monitor my generation.

Can anyone help me with instructions on how to read the AS230 meter as it seems to have 1 push button and I can't fathom out the various modes it will read. Also an explanation of the LEDs would be useful.

I've also got a CurrentCost clamp-on meter on the solar output and the grid connection, but obviously the grid connection can export as well as import but the monitor can't differentiate between the two. Has anyone managed to find a clever way to monitor just the demand inside the home - I looked at using multiple clamps inside the consumer unit but there isn't any spare space to do this.

Thanks

I have just started looking at solar as we are in the process of selling our house here and buying one with owned solar elsewhere. I am no expert but have dabbled in electronics and computer programming for years. I believe it shouldn't be too difficult to take an automatic reading from a monitor then deliberately switch on a 100 watt bulb for a few seconds and take another reading during that time. That way you can work out if you are exporting or importing electricity and store the information on your computer. I would think that taking readings say every 15 minutes would give a reasonable set of readings. At the same time it should be no problem to measure the light level so you would have a useful data set to work with to give a good idea as to how the system is doing. Obviously there would be no value in switching the light on when it is dark outside so again this could be done with the software.

EcoPaul

If you have a hot water tank and immersion heater you can get an immersun unit (there are other makes but I have an immersun) this unit connects to your supply and knows when you are exporting and will direct your surplus to your immersion heater before exporting any to the grid it also has a display that tells you exactly what you are putting into your hot water or how much you are exporting when hot water has reached temperature it can also power 2 other devices but it has to be something that can run on a variable input like another immersion heater or a storage heater

michaels

We do a bath and 4 showers morning and evening. I have left the gas on the usual schedule but set it down from 60 to 50 which should be ok (I think from memory the tank is 210l, it is 4 years old viessman so tank losses are negligible). Then I have the iBoost on the lower immersion (there are 2, the upper one is off) with the temp set at 70 so hopefully I can add up to 1 tankful from 50 to 70 using solar which I calc as about 5 units per day but the iBoost says we divert about 7 units. No doubt given our usage we still burn a fair amount of gas but I don't really want to put the immersion any hotter or have less energy stored than what 50 degreees gives us. Ironically it mweans that the less we generate the more likely we are to use it all.

We also have an electric car which unfortunately doesn't support being charged with a diverter so it is on a timer to charge when we are most likely to be generating most and takes generally another 5kw per day at 2.4kw (we no longer use the 6kw charger) so we have a good 'baseline' usage.

I don't thik the iBoost records howmuch is exported unless anyone knows otherwise?